In some plasma processing chambers, the upper electrode can be configured to execute in the grounded mode or the RF-powered mode. Generally speaking, the bottom electrode that supports the substrate may be powered with an appropriate RF power source (which may provide one or more RF signals to the bottom electrode). The upper electrode may be grounded as is conventional in a capacitively coupled plasma processing chamber or may be powered with one or more RF signals. When the upper electrode is configured to execute in the RF-powered mode, RF power is supplied to the upper electrode. When the upper electrode is configured to run in the grounded mode, the upper electrode is grounded.
While there exist many techniques to alternately couple the upper electrode to ground or to an RF source, engineers are constantly looking for ways to improve the reliability and the maintainability of the chamber. Given the high energy and high RF frequency involved in RF electrode operation, reliability and maintainability of the switching mechanism is paramount. If the switching from the RF-powered mode to the grounded mode (and vice versa) is improperly designed, arcing may result and may detrimentally affect the grounding and/or RF connection and may alter the process result from substrate to substrate. Furthermore, a more robust switching mechanism may extend the service interval, allowing the plasma processing system to operate for a longer period of time before maintenance and/or replacement is required.